Crystoleum

This process from “crystal” + “oleum” (oil), was a method of applying colour to an albumen print, popular from c.1880 to c.1910.

The albumen print was the first commercially viable way of producing a photographic print on paper from a negative, and crystoleum provided a method of colouring this print.

How it worked was the albumen print was pasted face down to the inside of a concave piece of glass. When the adhesive was dry, careful rubbing of the paper backing left only the trasparent emulsion on the glass.

This image could then be coloured by hand, using oil paints, and another piece of glass was added at the back which could also be coloured. The two pieces of glass were then bound together and the image was complete.